1. Field of the Invention
The present invention relates to a centering valve box adapter that supports and centers a bonnet over a valve box to maintain vertical access to the valve box nut to eliminate the need for excavation by preventing shifting of the valve box.
2. Description of the Related Art
The use of valve boxes is well documented in the field of municipal water supply. It is important to install valves at certain intervals within the underground piping so that segments can be opened or closed upon direction of the interested party (be it governmental or private).
It is typical to place a bonnet and vertical pipe over the valve box to allow access to the valve, and in particular to a valve nut that is operable rotationally around the nut vertical axis. The top of the vertical pipe is preferably placed flush with the ground or manufactured surface, and a cover can be provided to restrict unauthorized access to the valve. In theory, a worker can remove the cover and access the valve nut via the vertical pipe with the use of a T-wrench. However, a major problem arises when the valve box moves, shifts or settles and the valve nut is no longer accessible via the vertical pipe. In this situation, excavation of the valve may be necessary. Of course, the excavation is associated with major costs, both in time and in dollars.
Several products have been developed over the years to combat the problems normally associated with shifting or settling of the valve boxes.
One such product is disclosed in U.S. Pat. No. 4,534,378 to Gagas et al., which is titled Gate Valve Adaptor. It is disclosed in this patent that an adaptor is provided for supporting a key box on an underground gate valve. The adapter is taught to include a rectangular metal ring adapted to be seated on the gate valve bonnet flange. A number of radially extending arms are positioned to engage the lower edge of the key box bonnet, and a resilient ring is positioned between the adaptor ring and the key box flange. The rectangular metal ring appears to be configured to match a specific size gate valve bonnet flange. While not problematic in some circumstances, the metal ring may not be useful with gate valve bonnet flanges of dimensions other than a specific size. Also, there appears to be little lateral support for the metal ring to prevent lateral movement that could occur during shifting of the gate valve box. Further, vertical support of the bonnet is dependent upon maintaining the location of the metal ring on top of the gate valve bonnet flange.
U.S. Pat. No. 6,226,929 to Gagas is titled Liquid Infiltration Prevention Structures for Preventing Liquid Infiltration Manhole Assemblies Gate Valve Sealing Structures for Preventing Settling or Shifting of Key Box Bonnets and Method for Using Said Structures. The adaptor is taught to be provided with a resilient gasket to provide a cushion and create a seal for the bonnet on the gate valve. Yet, the gasket itself will nevertheless be subjected to the environmental stresses. It is possible that the resiliency of the gasket can lead to the gasket being compromised if the valve box shifts, settles or otherwise moves.
U.S. Pat. Nos. Des. 546,924 and Des. 548,309 are both to Gagas and titled Gate Valve Sealing Structure. The ornamental designs of the sealing structure appear to simply rest on the valve box near the top of the valve box.
A further product is made by American Flow Control and is named Trench Adapter and Retrofit Valve Box Insert. A self centering alignment ring is provided having a sliding adjuster. The alignment ring appears to rest on the valve box directly beneath the valve nut.
None of these designs incorporate a low profile retainer extending beyond the rim of the upper portion of the valve box, and none of these designs incorporate brackets for vertically and laterally supporting a bonnet.
None of these designs show an assembly with a perimeter entirely outside of rim of the valve box to provide an increased support for increased stability.
None of these designs show a method of assembling the assembly to prevent shifting and settling of the valve box.
Thus there exists a need for a centering valve box adapter that solves these and other problems.